DESCRIPTION: (Applicant's Abstract) Project ALERT is a school-based curriculum (eleven lessons in the 7th grade and a three-lesson booster in the 8th) to prevent/delay the use of alcohol, tobacco, and other drugs (ATOD) among young people by raising resistance self efficacy; modifying beliefs regarding ATOD norms; changing expectancies and intentions regarding ATOD use; and helping students identify and resist pro-drug pressures. An earlier evaluation of ALERT documented favorable effects on these cognitive factors and ATOD use among middle-school students. In this study we will create developmentally appropriate booster lessons extending the ALERT curriculum into the 9th, 10th, and 11th grades. Multi year outcomes will be compared across three conditions: a control (no ALERT) condition; the existing ALERT curriculum (7th and 8th grades); and the extended curriculum (7th thru 11th grades), called ALERT PLUS. Clusters of 48 high schools and their middle-school feeders will be randomly assigned to these conditions. Clusters will include public and Catholic schools in communities of varying size in the largely rural state of South Dakota. The study design will enable us to address current issues in generalizability (are social influence programs effective for young people of varying background characteristics and in varying school contexts), sustain ability (what can be done to prolong the favorable effects of middle-school prevention programs as teens move through their high-school years) and implementation (what school characteristics facilitate or undermine successful implementation of ATOD prevention curricula). Specific aims of the study are as follows. (1) Estimate the effects of the 7th and 8th grade curriculum on cognitive factors and ATOD use among a cohort of middle-school students in a rural state. (2) Estimate the effects of 9th to 11th grade booster lessons on cognitive factors and ATOD use as the middle-school cohort matures. (3) Explicate effects of ALERT and ALERT PLUS in analyses of rural/urban school context, mediating and moderating background factors, dose-response, and longitudinal transitions on ATOD use. (4) Describe program implementation and incorporate fidelity of implementation into outcome analyses. (5) Estimate the cost-effectiveness of Project ALERT and Project ALERT PLUS.